An important and essential function of the anterior lens capsule is to act as a filtration barrier to the movement of molecules into and out of the lens. We propose here to expand our previous morphological work on the capsule to include more detailed biochemical inquiries. Our main interest will center around (1) composition of the collagen and collagen associated proteins of this structure, and (2) their interactive properties as studied by in vitro gelation experiments. For the success of such studies isolation of the most intact form of the protein constituents is essential. To that end extensive use will be made of non-proteolytic and in some cases non-denaturing extraction procedures rather than the enzymic techniques now commonly employed. In addition, our preliminary work on the salt precipitation, sedimentation and thermal gelation of basement membrane collagen will enable the purification of the most intact, undenatured forms of this molecule before resorting to harsher techniques for chemical analysis. After isolation of non-degraded basement membrane collagen molecules chromatographic and enzyme digestion techniques will be used to determine the Alpha chain composition, the persistance of pro-collagen peptides and the nature of S-S bonded glycoproteins. After thorough investigation into molecular structure these data will be used to further refine our studies on the factors which influence the aggregation of basement membrane collagen into its peculiar three-dimensional architecture.